Method of coating wires for drawing



obtain benefits of the present invention.

United States Patent 3,082,129 METHOD OF COATING WIRES FOR DRAWING John A. Henricks, Logansport, Ind., assignor to Devex Corporation, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Dec. 7, 1956, Ser. No. 626,843 2 Claims. (Cl. 1486.24)

The present invention relates to the treatment and lubrication of ferrous metal wires for cold drawing.

This application is a continuation-in-part of my copending application Serial No. 274,839, filed March 4, 1952, now abandoned, which in turn is a continuation-inpart of my application Serial No. 193,290, filed October 31, 1950, now Reissue Patent No. 24,017, and formerly US. Patent No. 2,588,234.

Ferrous metal wires are generally annealed so thatthe drastic reduction of metal due to cold drawing may be withstood. After this annealing, the rod or wire stock is ordinarily pickled, coated with a hydrated lime or borax slurry, baked to dry the coating and to liberate hydrogen which may been absorbed by the salt in the pickling operation, and thereafter drawn through a die in which suitable soap-type lubricants or the like are applied to the stock just ahead of its entrance into the die.

It is an object of the present invention to provide an improved coating for applying to rods and Wires prior to drawing through the die.

It is also an object to provide a relatively dust fre-e and nonflaking coating for freshly pickled wire or rod stock prior to drawing through the die.

In accordance with the present invention, a prime coating of an alkali metal thiosulfate is applied to ferrous wire or rod stock before it is drawn through the die.

The prime coating is preferably applied by dipping previously pickled stock in an aqueous solution of the alkali metal thiosu'lfate to forrri a coating thereon. The stock is thereafter dried to eliminate water. It is then drawn through the die using a conventional drawing lubricant such as a soap and borax mixture, graphite or molybdenum sulfide at the die box so as to coat the work therewith immediately prior to drawing through the die.

The preferred thiosulfate salt used to form the prime coating is sodium thiosulfate. Some benefits of the present invention may also be obtained with thiosulfates of other alkali metal salts, such as hydrated or anhydrous thiosulfate of sodium and potassium (and preferably sodium) or other suitable metal salts, such as calcium, although if a salt' having deliquescent properties such as potassium, thiosulfate is used, the drawing operation should be performed relatively soon after the pickling and coating operation. The salt may be applied from anaqueous solutionwhich can be in'concentrations of as low as about one ounce per gallon of solution and still The salt may be used by itself or in conjunction with borax, lime, or other prime coating salts.

The thiosulfate salt is preferably used in amounts of about 10 to 20 ounces per gallon of aqueous solution although saturated solutions or even supersaturated solutions may be employed, even though such practice is expensive and tends to deposit a thicker thiosulfate coating than is generally desired.

Ordinarily the thickness of the thiosulfate coating upon a 3,082,129 Patented Mar. 19, 1963 2 drying is about .1 mil up to about 4 or 5 mils, although different thicknesses may be used depending upon the type of metal used, the durability and surface characteristics of the metal being drawn, and the severity of the size reduction in the wire drawing step.

The following example illustrates my invention:

Example 1 Low carbon steel rods were pickled in a 6% by weight solution of sulfuric acid at a temperature of about F. The rods were thereafter rinsed in water, dried, and subsequently immersed in an aqueous solution of sodium thiosulfate at a concentration of about 15 ounces per gallon. The rods were covered with a coating of sodium thiosulfate, which was dried to remove the water. The coated rods were then drawn through a die by using a conventional soap type lubricant. The drawn rods were examined and observed to have a bright and scratch-free surface.

In the above example, part of the sodium thiosulfate may be substituted for by a compatible alkali metal salt of a glass forming acid selected from amember of the group consisting of boric acid, silicic acid and phosphoric acid. However, not substantially more than 50 percent by weight of the thiosulfate salt should be replaced in order to obtain benefits of the present invention, and when the substitution is made, the glass forming alkaline salts are preferably present in amounts of about 20 to 30 percent by weight.

The preferred alkali metal salts of glass forming acids are sodium metasilicate and borax (Na B O -10H O). Suitable glass forming alkaline salts are (l) alkali metal silicates such as sodium silicate, sodium metasilicate, and sodium orthosilicate; and the silicate and tetrasilicate of potassium, and the metaand ortho-silicates of lithium and potassium, (2) alkali metal borates such as the anhydrous and hydrated sodium meta borates and sodium tetraborates, potassium metaand tetraborates and lithium metaand tetraborates, and (3) alkali metal phosphates such as the meta, pyro, monobasic, dibasic and tribasic phosphates of sodium and potassium; and the mono-, diand tribasic phosphates of lithium.

High carbon steel and stainless steel wire or rods may be substituted for the low carbon steel rod of the above example. Similar results are obtained when drawing the above types of ferrous metals.

It is to be understood that in accordance with the provisionsof the patent statutes, the particular form of prodobjects in an aqueous solution of a thiosulfate salt of an alkali metal so as to coat said object with undecomposed thiosulfate solution, drying said object to remove water and provide a dry coating of thiosulfate, and applying a drawing lubricant over said thiosulfate coating.

2. The method according to'claim 1 in which not substantially more than about 50% byweight of the thiosulfate is substituted by a glass forming alkaline salt selected from a member of the group consisting of alkali 2,558,234 Henricks Mar. 4, 1952 metal borates, silicates and phosphates. 2,876,150 Singer Mar. 3, 1959 References Cited in the file of this patent FOREIGN PATENTS 5 131,106 Austria Ian. 10, 1933 UNITED STATES PATENTS 612,728 Germany May 3, 1935 224,829 Kenerson Feb. 24, 1880 2,008,939 Tufts July 23, 1935 OTHER REFERENCES 2,074,224 Johnson Mar. 16, 1937 Mellor: Modern Inorganic Chemistry, page 569,

2,550,660 Amundsen et a1. Sept, 4, 1948 edition of 1939. 

1. A METHOD OF PREPARING FERROUS METAL OBJECTS SUCH AS RODS AND WIRES FOR COLD DRAWING BY IMMERSING SAID OBJECTS IN AN AQUEOUS SOLUTION OF A THIOSULFATE SALT OF AN ALKALI METAL SO AS TO COAT SAID OBJECT WITH UNDECOMPOSED THIOSULFATE SOLUTION, DRYING SAID OBJECT TO REMOVE WATER AND PROVIDE A DRY COATING OF THIOSULFATE, AND APPLYING A DRAWING LUBRICANT OVER SAID THIOSULFATE COATING. 